Fluid handling devices, such as centrifugal pumps, may be used in a variety of applications to move fluid through a system. A centrifugal pump includes a rotating impeller that receives a fluid flow along its rotating axis, and accelerates or pushes the fluid radially outward through an outlet. In certain centrifugal pumps, a mechanical seal is utilized in the location where the rotating shaft that carries the impeller passes through a stationary housing. In some examples, the mechanical seal may be located in a seal cavity defined by the impeller, a portion of the stationary housing, and a gland plate.
In normal operation, a portion of the fluid that is being moved by the centrifugal pump will flow into the seal cavity and contact the mechanical seal. Such fluid may thereby provide lubrication and cooling to the mechanical seal. However, in some cases the centrifugal forces generated by the impeller in the seal cavity may pull fluid away from the mechanical seal, and one or more air pockets may form adjacent to the mechanical seal. The formation of such air pockets can increase local friction and temperatures of the mechanical seal components, thereby causing accelerated wear of such components and correspondingly reducing the useful life of the seal. Such increased heat may also affect other regions of the pump such as, for example, causing compression set in elastomeric O-rings leading to leaks and failures in adjacent areas.